The decades-long, yet-to-be-completely-explained gamma-ray glow at the center of the Milky Way may be the first observational evidence of the existence of dark matter. This discovery, based on cross-validation of supercomputer simulations and space telescope observation data, brings new hope for revealing this mysterious component in the universe.
Dark matter is thought to make up a large portion of the total mass of the universe and is key to maintaining the structure of galaxies. However, since it does not emit light and does not interact with electromagnetic waves, direct detection is extremely difficult. There have long been two mainstream explanations for the abnormal gamma ray signal in the center of the Milky Way: the collision and annihilation of dark matter particles, or the radiation from a large number of millisecond pulsars.
Research recently published in Physical Review Letters has made key progress. A team led by the Potsdam branch of the Leibniz Institute for Astrophysics in Germany used supercomputers to construct a dark matter distribution model that includes the formation history of the Milky Way for the first time. The simulation results show that dark matter collides frequently in the central region of the galaxy due to its extremely high density. Its predicted gamma ray distribution is highly consistent with the actual observation map of the Fermi Gamma-ray Space Telescope.
Still, the scientific community remains cautious. The millisecond pulsar hypothesis can also explain some of the observed characteristics, but this theory requires the assumption that there is a population of pulsars that far exceeds the number of current observations, which makes it challenging.
The construction of the next-generation observation equipment Cherenkov Telescope Array Observatory (CTAO) is advancing, which may provide decisive data. Its unprecedented sensitivity and resolution can distinguish the energy characteristics of gamma rays, thereby determining whether the signal originates from dark matter collisions or pulsar radiation.
Currently, the research team is applying the same model to dwarf galaxies orbiting the Milky Way to further test the dark matter hypothesis by comparing predictions with future high-resolution observational data. Regardless of the outcome, this exploration process will deepen human understanding of the composition of galaxies and the nature of the universe.